Variable displacement swash plate type compressor

ABSTRACT

Provided is a variable displacement swash plate type compressor including a cylinder block having a plurality of cylinder bores, a drive shaft rotatably supported by the cylinder block, a lug plate fixedly installed at the drive shaft, a swash plate rotated by the lug plate to vary its inclination angle, and pistons reciprocally accommodated in the cylinder bores depending on rotation of the swash plate, the compressor including a projection projecting from the lug plate toward the swash plate and disposed only behind the rotational direction of the drive shaft, a slope formed on the rear part of the lug plate at one side of the projection, an arm projecting from the swash plate toward the lug plate, a first guide coupled to the arm in front of the rotational direction of the drive shaft to move along the slope in a contact manner, and a second guide coupled to the arm adjacent to the projection to move along the slope in a contact manner.

TECHNICAL FIELD

The present invention relates to a variable displacement swash platetype compressor, and more particularly, to a variable displacement swashplate type compressor capable of preventing distortion of the swashplate to smoothly change an inclination angle of the swash plate andpreventing abnormal wearing of a power transmission member and a slopemovement member to increase compression efficiency and reducemanufacturing cost.

BACKGROUND ART

Various kinds of compressors such as a scroll type or a swash platetype, are used in various fields using hydraulic pressure, for example,an air conditioning apparatus. In general, swash plate type compressorsusing an inclination angle of a swash plate and employing a plurality ofcylinders have been widely used to more precisely perform hydrauliccontrol.

Among them, a variable displacement swash plate type compressor capableof continuously varying an inclination angle of a swash plate dependingon variation in thermal load to control strokes of pistons to therebyperform precise flow rate control and preventing abrupt variation intorque of an engine due to the compressor to improve ride comfort of avehicle is being widely used.

In a conventional variable displacement swash plate type compressor,since a power transmission element fixed to a drive shaft andtransmitting power from a rotating lug plate to a swash plate isseparate from an element for slope movement of the swash plate, the lugplate may be in direct contact with the swash plate, thus rapidlywearing a compressor member and disturbing smooth slope movement of theswash plate.

Therefore, a swash plate type compressor in which a component forrotational power transmission and a component for slope movement guideare integrated as a single body has been proposed. For example,disclosed hereinafter is a variable displacement swash plate typecompressor including slide blocks installed at both side ends of a pinpassing through a projection projecting from a center part of a frontsurface of a swash plate such that the slide blocks perform the powertransmission and the slope movement guide.

FIGS. 1 to 4 show an example of a conventional variable displacementswash plate type compressor disclosed in Korean Patent Application10-2006-0120155, which will be briefly described with reference to thedrawings.

FIG. 1 is a perspective view of a conventional variable displacementswash plate type compressor 10. Slide blocks 43 are installed at bothsides of a projection 41 by inserting a pin into the projection 41formed at a front center part of a swash plate 40. Peripheral surfacesof the slide blocks 43 roll along slopes 34 formed in a powertransmission groove 31 of a lug plate 30 to enable slope movement of theswash plate 40. In addition, the both surfaces of the slide blocks 43transmit rotational movement of the lug plate 30 using side surfaces 35of the power transmission groove 31. That is, direct contact between thelug plate 30 and the swash plate 40 can be prevented by a rear groove 33in a direction of a drive shaft 20 and the slide blocks 43 in adirection of the sidewalls 35 of the lug plate 30.

FIG. 2 is an exploded perspective view of the conventional variabledisplacement swash plate type compressor, showing components related tocoupling the lug plate 30 and the swash plate 40 of the compressor 10.The sidewalls 35 of the power transmission groove 31 of the lug plate 30are formed at front and rear sides in a rotational direction of thedrive shaft 20. The power transmission groove 31 is constituted by twoslopes 34 and a rear groove 33 disposed between the slopes 34. The slideblocks 43 installed at both sides of the projection 41 disposed at afront center of the swash plate 40 roll along the slopes 34 to vary aninclination angle of the swash plate 40. In addition, the rear groove 33prevents direct contact between the lug plate 30 and the swash plate 40to minimize wearing of members during power transmission and slopemovement guide. Meanwhile, side grooves 32 are formed in the bothsidewalls of the power transmission groove 31 to prevent the swash plate40 from coming off due to insertion of a pin 42 into the grooves 32,when the swash plate 40 moves along the slope.

FIG. 3 is a perspective view showing a rear surface of the lug plate 30of the conventional variable displacement swash plate type compressor.In addition to the description of FIG. 2, a reinforcement rib 36connecting a rear surface of the sidewall 35 of the lug plate 30 to arear surface of the lug plate 30 is configured to prevent deformation ofthe lug plate 30 due to rotational movement thereof. Inner surfaces 37of the sidewalls 35 of the lug plate 30 transmit rotational movement ofthe lug plate 30 to the swash plate 40 through the slide blocks 43.

FIG. 4 is a perspective view showing a front surface of the swash plate40 of the conventional variable displacement swash plate typecompressor. In addition to the description of FIG. 2, an insertion hole44 is formed in the swash plate 40. A sleeve inserted into the driveshaft through the insertion hole 44 is coupled to the swash plate 40 toprevent the swash plate 40 from being separated from the center of thedrive shaft.

According to the conventional art, the side surfaces of the slide blocksperform power transmission and the peripheral surfaces of the slideblocks perform slope movement guide to prevent direct contact betweenthe lug plate and the swash plate, thereby minimizing wearing of themembers and facilitating slope movement of the swash plate.

DISCLOSURE OF INVENTION Technical Problem

However, since a conventional variable displacement swash plate typecompressor includes a plurality of cylinders in which coolant is suckedor discharged, a resultant force of pistons installed in the cylindersmay not be aligned with a rotational center of the drive shaft. In thiscase, a cylinder block and a swash plate are distorted so that smoothslope movement of the swash plate, a major component of the swash platetype compressor, cannot be performed. In addition, abnormal wearing of apower transmission part is accelerated, thus decreasing compressionefficiency and durability of components.

Therefore, an object of the present invention is to provide a variabledisplacement swash plate type compressor capable of effectivelypreventing distortion of a swash plate.

Technical Solution

The foregoing and/or other objects of the present invention may beachieved by providing a variable displacement swash plate typecompressor including a cylinder block having a plurality of cylinderbores, a drive shaft rotatably supported by the cylinder block, a lugplate fixedly installed at the drive shaft, a swash plate rotated by thelug plate to vary its inclination angle, and pistons reciprocallyaccommodated in the cylinder bores depending on rotation of the swashplate, the compressor including:

a projection projecting from the lug plate toward the swash plate anddisposed only behind the rotational direction of the drive shaft;

a slope formed on the rear part of the lug plate at one side of theprojection:

an arm projecting from the swash plate toward the lug plate;

a first roller coupled to the arm in front of the rotational directionof the drive shaft to move along the slope in a contact manner; and

a second roller coupled to the arm adjacent to the projection to movealong the projection and the slope in a contact manner.

Here, the slope may have a rear groove, and an end of the arm may beinserted into the rear groove.

In addition, the first roller and the second roller may be coupled tothe arm via a pin passing through the arm.

Further, the projection 135 may have a side groove 132 formed in itsinner surface, and one end of the pin 142 may be inserted into the sidegroove 132.

Furthermore, the inner surface, the slope 134 and the rear groove 133 ofthe projection 135 may have a step shape.

In addition, the rollers 143A and 143B may have circular cross-sections.

Further, the rollers may have polygonal cross-sections.

Furthermore, when seen from the drive shaft, a tip of the first rollermay be farther from a line connecting from a center of the cylinderblock to a center of the arm than that of the second roller.

In addition, when seen from the drive shaft, a distance L from the tipof the first roller 143A to the line connecting from the center of thecylinder block to the center of the arm may be 0.4 times or more aradius R of a circle formed by centers of the plurality of cylinderbores 111.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects and advantages of the present invention willbecome apparent and more readily appreciated from the followingdescription of exemplary embodiments, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a perspective view of a conventional swash plate typecompressor;

FIG. 2 is an exploded perspective view of the conventional swash platetype compressor;

FIG. 3 is an enlarged view of a rear surface of a lug plate of theconventional swash plate type compressor;

FIG. 4 is an enlarged view of a front surface of a swash plate of theconventional swash plate type compressor;

FIG. 5 is a plan view of a swash plate type compressor in accordancewith an exemplary embodiment of the present invention;

FIG. 6 is a front view of the swash plate type compressor in accordancewith an exemplary embodiment of the present invention;

FIG. 7 is a transverse cross-sectional view of the swash plate typecompressor in accordance with an exemplary embodiment of the presentinvention;

FIG. 8 is a side cross-sectional view showing a position of a firstroller of the swash plate type compressor in accordance with anexemplary embodiment of the present invention;

FIG. 9 is a perspective view of the swash plate type compressor inaccordance with an exemplary embodiment of the present invention; and

FIG. 10 is an exploded perspective view of the swash plate typecompressor in accordance with an exemplary embodiment of the presentinvention.

MODE FOR THE INVENTION

Reference will now be made in detail to a variable displacement swashplate type compressor in accordance with an exemplary embodiment of thepresent invention illustrated in the accompanying drawings in comparisonwith a conventional art.

FIGS. 5 to 10 show the variable displacement swash plate type compressorin accordance with an exemplary embodiment of the present invention.

FIG. 5 is a plan view of the variable displacement swash plate typecompressor 100 in accordance with an exemplary embodiment of the presentinvention. A first roller 143A and a second roller 143B are installed atboth side ends of a pin 142 inserted in a vertical direction of an arm141 projecting from a front center of a swash plate 140 toward a lugplate 130. Here, the roller located in front of a rotational directionof the drive shaft 120 is referred to as the first roller, and theroller located behind the rotational direction of the drive shaft 120 isreferred to as the second roller. Meanwhile, the pin 142 may passthrough the center of the arm 141 or may be fastened to the arm 141 bywelding, etc. The first roller 143A and the second roller 143B may havea circular cross-section, but are not limited thereto, and may have anyshape that can effectively transmit slope movement of the swash plate140 through rolling movement, for example, a polygonal shape.

The second roller 143B located behind the rotational direction of thedrive shaft 120 is configured to transmit rotational movement of the lugplate 130 from a projection 135 projecting from a rear surface of thelug plate 130 toward the swash plate 140 to the arm 141 through its sidesurface. As a result, the rotational movement of the lug plate 130 fixedto the drive shaft 120 is transmitted to the swash plate 140. However,since there is no projection formed in front of rotational direction ofthe lug plate 130, as their is behind the rotational direction, thefirst roller 143A located in front of the rotational direction of thedrive shaft 120 does not transmit the rotational power to the swashplate 140. Since a position of the first roller 143A is not limited bythe projection, the first roller 143A can be located anywhere within arange of the length of the pin 142. This means that the position of thefirst roller 143A can be set depending on a position at which aresultant force of a plurality of pistons is actually applied departingfrom a center of the drive shaft 120.

Meanwhile, since the rear part of the lug plate 130 has a slope 134 atone side of the projection 135, peripheral surfaces of the first roller143A and the second roller 143B roll along the slope 134 to guide slopemovement of the swash plate 140.

A stopper 121 and a snap ring 122 disposed at a rear surface of theswash plate 140 function to stop movement of a sleeve and the swashplate 140 when rotation of the drive shaft 120 is stopped.

FIG. 6 is a front view of the variable displacement swash plate typecompressor in accordance with an exemplary embodiment of the presentinvention. In addition to the description of FIG. 5, a spring 150 isaxially installed from a rear surface of the lug plate 130 to the swashplate 140. When the spring 150 is slackened, the swash plate 140 has aminimum inclination angle. When the spring 150 is compressed due to apressure difference between a swash plate chamber and the cylinder bore,an inclination angle of the swash plate 140 is determined by thepressure difference. That is, when the pressure difference between theswash plate chamber and the cylinder bore is maximized, the inclinationangle of the swash plate 140 also arrives at a maximum value, and theswash plate 140 is inclined until a lower part of the swash plate 140 isin contact with the lug plate 130.

FIG. 7 is a transverse cross-sectional view of the variable displacementswash plate type compressor in accordance with an exemplary embodimentof the present invention.

Pistons 112 are installed in cylinder bores 111 via shoes 110 connectedto the swash plate 140 such that the pistons 112 reciprocate in thecylinder bores 111 in a lateral direction along the slope of the swashplate 140 to repeatedly suck and discharge coolant. At this time, thecoolant is supplied from a suction chamber 172 installed in a rearhousing 170 of the variable displacement swash plate type compressorinto the cylinder bores 111 through a suction port 171. Similarly, thecoolant is discharged from the cylinder bores 111 to a discharge chamber173 installed in the rear housing 170 through a discharge port 174.

FIG. 8 is a side cross-sectional view showing a position of the firstroller 143A of the variable displacement swash plate type compressor inaccordance with an exemplary embodiment of the present invention. Whenseen from a longitudinal direction of the drive shaft, the plurality ofcylinder bores 111 are disposed in a peripheral direction of a cylinderblock at predetermined angular intervals. At this time, a resultantforce of the pistons actually applied to the cylinder bores 111 istypically located at a position 113 adjacent to a compression side, nota center of the cylinder block. Therefore, as described in FIG. 5, whenthe position of the first roller 143A is located to correspond to theposition 113 where the resultant force of the pistons is applied, it ispossible to prevent distortion of the swash plate which may generateddue to misalignment of the position 113 where the resultant force of thepistons is applied and the center of the cylinder block. Here, adistance L from a line connecting the center of the cylinder block andthe center of the arm to a position where a tip of the first roller 143Ais located may be 0.4 times or more a radius R of a circle formed ofcenters of the cylinder bores 111 to stably support a load and smoothlyguide the roller along the slope 134.

In addition, when seen from the drive shaft, a tip of the first roller143A may be farther from the line connecting the center of the cylinderblock and the center of the arm 141 than a tip of the second roller143B. Since the slope before the rotational direction about a reargroove 133 may have a larger width, the width of the first roller 143Acorresponding thereto may be increased to accomplish stable guidance andsupport functions.

FIG. 9 is a perspective view of the variable displacement swash platetype compressor in accordance with an exemplary embodiment of thepresent invention. The first roller 143A and the second roller 143B rollalong the slope 134 formed at the rear surface of the lug plate 130 tomove the swash plate 140 in a slant direction, and the side surfaces ofthe second roller 143B transmit power (rotational movement) of the lugplate 130 to the swash plate 140 through a power transmission surface137 formed at an inner sidewall of the projection 135.

In addition, a rear groove 133 is formed in a bottom center of the slope134, and an end of the arm 141 is inserted into the rear groove 133 tobe hooked thereinto upon reverse rotation of the lug plate 130, therebypreventing the lug plate 130 from loosening.

In particular, the slope 134 by the side of the projection 135 is formedadjacent to the inner surface of the projection 135 in the vicinity ofthe rear surface 133.

Typically, the power transmission surface 137, the slope 134 and therear groove 133 form a step shape. Therefore, power transmission to theswash plate 140 and guidance of the swash plate 140 can besimultaneously performed by the power transmission surface 137 formed atthe inner surface of the projection 135 and the slope 134 adjacent tothe power transmission surface 137.

In addition, a side groove 132 is formed in the inner surface of theprojection 135, and one end of the pin 142 is inserted into the sidegroove 132. Since the pin 142 is inserted into the side groove 132, itis possible to prevent the swash plate 140 from being pushed toward thepiston upon initial movement or stop of the compressor when a gaspressure is not properly applied.

FIG. 10 is an exploded perspective view of the variable displacementswash plate type compressor in accordance with an exemplary embodimentof the present invention. In addition to the description of FIGS. 5 to9, it will be appreciated that the swash plate 140 includes a sleeve 160for smoothly moving the swash plate 140 along the drive shaft 120. Thesleeve 160 has a coupling hole 162 formed at its center such that thesleeve 120 can move along the drive shaft 120 in a longitudinaldirection thereof, and guide projections 161 are formed at both sidesabout the coupling hole 162. A guide groove (not shown) is formed in aninner surface of the insertion groove 144 of the swash plate 140 to bereadily coupled to the guide projections 161 of the sleeve 160. Thesleeve 160 connected to one end of the spring 150 moves toward the lugplate 130 along the drive shaft 120 depending on contraction of thespring 150 to tilt the swash plate 140. When the spring 150 isslackened, the sleeve 160 moves toward the swash plate 140 along thedrive shaft 120 to stand the swash plate 140 in an upright position.

While this invention has been described with reference to exemplaryembodiments thereof, it will be clear to those of ordinary skill in theart to which the invention pertains that various modifications may bemade to the described embodiments without departing from the spirit andscope of the invention as defined in the appended claims and theirequivalents.

INDUSTRIAL APPLICABILITY

As can be seen from the foregoing, a variable displacement swash platetype compressor in accordance with an exemplary embodiment of thepresent invention can prevent distortion of a swash plate, which may becaused due to offset of the center of gravity of the swash plate towarda compression-side cylinder. Prevention of distortion of the swash platemeans smooth slope movement of the swash plate and prevention ofabnormal wearing of related members such as a projection, and a roller.In addition, the projection is formed at only one side behind arotational direction of a drive shaft to transmit rotational movement ofthe lug plate, thereby reducing manufacturing cost through thelight-weighted compressor.

Moreover, since there is no projection in front of the rotationaldirection, position of a first roller can be varied without limitationdue to the projection. As a result, the position of the first roller canbe flexibly set depending on actual compression conditions, in which aresultant force of pistons is applied, to prevent abnormal wearing ofmembers and remarkably improve durability of the compressor.

1-9. (canceled)
 10. A variable displacement swash plate type compressorincluding: a cylinder block having a plurality of cylinder bores; adrive shaft rotatably supported by the cylinder block; a lug platefixedly installed at the drive shaft; a swash plate rotated by the lugplate to vary its inclination angle; and pistons reciprocallyaccommodated in the cylinder bores depending on rotation of the swashplate, the compressor comprising: a projection projecting from the lugplate toward the swash plate and disposed only behind the rotationaldirection of the drive shaft; a slope formed on the rear part of the lugplate at one side of the projection; an arm projecting from the swashplate toward the lug plate; a first guide coupled to the arm in front ofthe rotational direction of the drive shaft to move along the slope; anda second guide coupled to the arm adjacent to the projection to movealong the slope.
 11. The variable displacement swash plate typecompressor according to claim 1, wherein the second guide has at leastone contact surface contacted with the projection.
 12. The variabledisplacement swash plate type compressor according to claim 1, whereinthe slope includes a first slope opposing the first guide and a secondslope opposing the second guide, and the first slope and the secondslope are spaced apart from each other by a predetermined distance. 13.The variable displacement swash plate type compressor according to claim1, wherein the first guide and the second guide move along the slope ina contact manner.
 14. The variable displacement swash plate typecompressor according to claim 4, wherein the contact area of the firstguide is larger than the contact area of the second guide.
 15. Thevariable displacement swash plate type compressor according to claim 4,wherein the slope includes a first slope along which the first guidemoves in a contact manner and a second slope along which the secondguide moves in a contact manner, and the first slope and the secondslope are spaced apart from each other by a predetermined distance. 16.The variable displacement swash plate type compressor according to claim1, wherein the slope has a rear groove and an end of the arm is insertedinto the rear groove.
 17. The variable displacement swash plate typecompressor according to claim 1, wherein the first guide and the secondguide are coupled to the arm via a pin passing through the arm.
 18. Thevariable displacement swash plate type compressor according to claim 8,wherein through-holes through which the pin passes are formed in thefirst guide and the second guide respectively.
 19. The variabledisplacement swash plate type compressor according to claim 8, whereinthe projection has a side groove formed in its inner surface, and oneend of the pin is inserted into the side groove.
 20. The variabledisplacement swash plate type compressor according to claim 7, whereinthe projection has a side groove formed in its inner surface, and theside groove, the slope, and the rear groove are formed sequentially inthe direction of the drive shaft.
 21. The variable displacement swashplate type compressor according to claim 1, wherein the first guide andthe second guide have circular cross-sections.
 22. The variabledisplacement swash plate type compressor according to claim 1, whereinthe first guide and the second guide have polygonal cross-sections. 23.The variable displacement swash plate type compressor according to claim1, wherein the first guide and the second guide roll on the slope. 24.The variable displacement swash plate type compressor according to claim1, wherein, when seen from the drive shaft, a tip of the first guide isfarther from a line connecting from a center of the cylinder block to acenter of the arm than that of the second guide.
 25. The variabledisplacement swash plate type compressor according to any one of claim1, wherein, when seen from the drive shaft, a distance (L) from the tipof the first guide to the line connecting from the center of thecylinder block to the center of the arm is 0.4 times or more a radius(R) of a circle formed by centers of the plurality of cylinder bores.